Generally, the top surface of a light-emitting diode is roughened to reduce total reflection and improve the light extraction efficiency. The process of roughening the top surface includes dry etching and wet etching. Dry etching could control the roughening region precisely, but the cost is higher. The cost of wet etching is lower, but the top surface under the bonding pad is usually laterally etched during the process of wet etching and causes the peeling of the bonding pad easily.
As FIG. 1 shows, a light-emitting diode 1 comprises a substrate 8, a first semiconductor layer 12 having a first polarity, such as a n-type GaN layer, on the substrate 8, an active layer 10 for emitting light on the first semiconductor layer 12, a second semiconductor layer 11 having a second polarity, such as a p-type GaN layer, on the active layer 10, a conductive oxide layer 2 on the second semiconductor layer 11, and a second pad 9 is formed on the side of the substrate 8 opposite to the first semiconductor layer 12, wherein the conductive oxide layer 2 has a rough top surface 21 and a bonding pad 3 is formed on the top surface 21. When a portion of the top surface 21 under the bonding pad 3 is etched, the adhesion between top surface 21 and the bonding pad 3 decreased, and the bonding pad 3 is peeled easily from the top surface 21.